The quality and efficaciousness and in some instances safety of non-durable products deteriorate over time, requiring the packaging within which they are contained to display a “Use By”, “Best Before”, “Expiration” or other date to indicate when the product will become unsuitable for use. Many products deteriorate at an accelerated rate once the packaging within which they are contained has been opened, the causes of which can be physico-chemical degradation due to time, exposure to excessive temperature, humidity, light and air and or microbial contamination. When the deterioration of a product after its opening could cause harm to the consumer, for example the degradation of the U.V. protection of a sun care product or the potential for microbial contamination of a mascara product, the period of time that the product will remain safe to use after opening or “Period after Opening” is often displayed on the product package. However, consumers frequently overlook or disregard the “Use By” or “Period after Opening” information provided, or fail to remember when a product package was first opened, with sometimes deleterious effects to product quality, health and safety.
With increasing consumer demand for non-durable products with improved quality, safety and lower preservative content, several improvements to the packaging for non-durable products have been suggested. GB2387941 describes a closure for preventing the opening of a bottle after an expiry date and consists of a conventional cap with an internal thread which mates with a threaded sleeve situated within a recess about the neck of a bottle. The sleeve is prevented from rotating about the neck of the bottle by lugs, manufactured from a bio-degradable plastics material, formed on the sleeve and located within indents formed on the neck of the bottle so that the torque required to remove or secure the cap to the bottle is transferred to the lugs. Once the plastic has degraded to a sufficient extent, the force required to remove the cap causes the lugs to shear, thus enabling the sleeve to rotate with the cap about the neck of the bottle, thereby preventing its removal. However, due to the imprecise nature of predicting when the bio-degradable material will degrade sufficiently for the lugs to shear, especially when exposed to changing conditions of temperature and humidity, it is difficult to ensure that the removal of the cap will be prevented within an acceptable time tolerance, thereby rendering the device impracticable for use in most product applications.
FR2887646 describes a time-indicating unit incorporated into the packaging for a fluid product-dispensing device, to provide a visual indication of elapsed time, to reduce the risk to a consumer caused by using a device containing expired product. The time-indicating unit is automatically activated by means of a push button upon first use of the product, but suffers the disadvantage that the user is relied upon to correctly interpret and act in accordance with the indication provided.
A number of time-temperature indicators have become available. Timestrip®, produced by Timestrip Plc (UK), for example, is a label-type device which relies on the migration of a tinted liquid through a micro-porous material at a rate dependant on temperature to provide an indication of time elapsed and is designed to monitor the shelf life of a wide range of opened or un-opened products to provide the consumer with a visual indication of when a product has reached the end of its useful life but suffers the disadvantage that the user is relied upon not only to activate and attach the device to the product package but also to correctly interpret and act in accordance with the indication provided. Fresh-Check® produced by the Temptime Corporation (USA), and MonitorMark™, produced by the 3M Corporation (USA), are label type time-temperature indicating devices designed to be affixed to or placed within the packaging for non-durable products and rely, respectively, upon the gradual darkening of a chemical indicator and the migration, at a rate dependant upon time and temperature, of a coloured indicator along a wicking material to provide the end user with a visual indication of when a product has reached the end of its useful life but, once again, suffer the disadvantage that the user is relied upon to correctly interpret and act in accordance with the indication provided.
To ensure product quality and efficacy and to safeguard the health and safety of consumers, a need therefore exists to prevent the use of non-durable products once the useful life of the product has been exceeded.